1. Field of the Invention
This invention relates to wiring boards that comprise magnetic bodies that exhibit outstanding magnetic loss characteristics at high frequencies, and more particularly to wiring boards such as flexible wiring boards and flexible flat cables that comprise multilayer or unilayer wiring boards or high-frequency current suppression bodies wherein magnetic loss materials are used that exhibit outstanding complex permeability characteristics and are effective in suppressing electromagnetic interference and spurious radiation that are problematic in active devices that operate at high speed, high-frequency electronic components, and electronic equipment mounted thereon.
2. Description of the Related Art
In recent years, the proliferation of highly integrated semiconductor devices has been remarkable which operate at high speed. Examples include the random access memory (RAM), read only memory (ROM), microprocessor (MPU), central processing unit (CPU), image processing arithmetic logic unit (IPALU), and other logic circuit devices. In these active devices, higher speeds are being achieved at a prodigious rate in terms of calculating speed and signal processing speed, and the electrical signals propagated through the high-speed electronic circuits have become a major cause of inductive and high-frequency noise because of the rapid voltage and current changes associated therewith. Meanwhile, the trend toward lighter weight, thinner profile, and smaller size in electronic components and electronic equipment continues rapidly and unabatedly. In conjunction with that trend, the integration levels being achieved in semiconductor devices and the higher electronic component mounting densities being realized in printed wiring or circuit boards are also remarkable. Accordingly, electronic devices and signal lines that are integrated or mounted overly densely become extremely close to each other, and the situation is now such that, in conjunction with the higher signal processing speeds being achieved, as remarked earlier, high-frequency spurious radiation noise is easily induced.
Problems have been pointed out with spurious radiation from power supply lines going to active devices in such recent electronic integrated devices and wiring boards, against which such measures as the insertion of decoupling condensers or other concentrated constant components into the power lines have been implemented.
However, because the noise generated in higher speed implementations of electronic integrated devices and wiring boards contains harmonic components, signal paths exhibit a distributed constant behavior, and situations have arisen where measures against noise that presume conventional concentrated constant circuits are ineffective.
Similar problems have arisen also, inside electronic equipment, relating to connections between boards, and to the flexible wiring or printed circuit boards (FPCs) or flexible flat cables (FFCs) (hereinafter both referred to by the generic term flexible wiring or printed circuit board (FPC)) mounted to electronic components.